Helicopter rotors have heretofore been constructed to permit folding of the blade about the rotor to decrease the space required for storing the aircraft. Many types of rotor blades are attached to the rotor hub by means of a pair of blade bolts. In one type of rotor, removal of one of the blade bolts permits the blade to pivot around the remaining bolt into a folded position. The bolt that is removed can then be used to lock the blade pitch change mechanism to avoid transmittal of the blade droop moment to the rotor control system. A second type of rotor hub and blade folding system is described in U.S. Pat. No. 3,625,631 to Covington Jr. et al.
To make the blade folding system more reliable and safer there exists a need for a latch mechanism to insure that the bolts are held securely in place during flight and to make possible easy inspection by ground crew members to insure that the bolts and lock mechanism are in the correct position for either flight or storage.